Color couplers for color development



color photography and it includes Patented May 8, 1945 uurrso i STATES ATENT orifice 2,375,344 COLOR COUPLERS FOR COLOR DEVELOPMENT Pierre Bruylants, Winxele-Velthem (Lowen); and Philibert Leopold Jozef Raymond Merclrx,

Berchem-Antwerp, Belgium; vested in the Alien Property Custodian No Drawing. Application May'20, 1941, Serial No. 394,290. In Great Britain March 13, 1940 2 Claims.

. Our invention relates to color photographic images and to means for producing same. More I particularly our invention relates to a process and material for color development in connection with v also the images obtained therewith. 1

It is an object of our invention to provide for an improved process of producing color photographic images by means of color couplers.

particularly useful color couplers as well as photographic emulsions or sensitive layers, in which such color couplers are incorporated, and photographic materials comprising a sensitive layer with a content of such a-color coupler.

Still other objects of our invention will appear as the specification proceeds. i I -It is known thatcolorphotographic image can be obtained by the use of such developers that form colored and-insoluble oxidation products during development, the product thus formed 001-. oring the gelatine adjacent to the developed silver. It is also known that colored images can be formed by the addition to the developing agents of certain products, called color couplers,

which couple with the oxidation products of the stances.

Hitherto many chemical compounds have been either used or proposed as color couplers. Among others have become known substituted and unsubstituted phenols and naphthols, nitrophenylacetonitriles, derivatives of acetamides, distinguished by the presence of an acidic methylene group, lsoxazolones and coumaranones.

United States Letters Patent No. 1,969,479 w' Seymour'discloses amongst others photographic developers containing as a color coupler a hydrazone of an acyl acetic acid ester.

As far as we are aware, no theory hitherto has been put forward in connection with the process of color development that will forecast with practical certainty whether or not a given prodready known it has not always been possible to find such color couplers which, with the oxida. tion product of the developing a ent,-give the desired tone morepartic 15 compounds containing also one or sever (ones-6y colors already formed or still to be formed in the other layers of a photographic material oompris-.

ing several layers. The fact that it is desirable only to use such color couplers, which form coloring substances insoluble in water and-which simultaneously resist the subsequent photographic baths restricts considerably the number of the,

color couplers that can be used.

Now we have found a newclass of color cou- 10 plers very useful for color development. This new class of color couplers includes the monoand poly-hydrazones being the products of condensation ofone or more hydrazides, which contain at least one reactive methylene group, with tive methylene groups. These new color .00 piers contain thus at least two reactive methylene groups separated from each other by a chain comprising what we call the hydrazine radical 0 =N NH, and theymay for instance on principle be produced by the condensation of an apylhydrazine with a keto compound containing at least one reactive methylene group; no pyrazolone derivatives are formed during this'condensation reaction,'as the analysis of the products shows.

Examplesof our new color couplers are: 1

Ha developingagent and thus form coloring sub- Cyanaoetylhydrazoneoi acetoacetic ethyl ester 2 CsH5-CO-CHr-C-COQC1H;

- Para-nit: hen lace lh drazone oibe o lacetic eth lestci v ulerlywitnresardtotheu y reac e or

f, Example 2:

Example 7: a magenta color.

intervention of organic solvents.

- acid esters.

. Monoeyanacetylhydrazone oi'dikctohydroindene These compounds can be obtained by the methods described in Berichte der deutschen Chemischen Gesellschaft, vol. 2'7, p. 688, vol. 40,

" p, 712, and vol. 41, D. 643.

On development with diethyl paraphenylenediamine as developing agent in conjunction with,

one of the above color couplers, .we get with the compound cited in an orange color,

a red color,

a yellow color, i

a magenta color,

a magenta color,

an orange color,

Example 1:

Example 3: Example 4: Example 5: Example 6;

I The new color couplers allow to obtain during 1 development particularly beautiful and bright.

colors. 7 a

Our color couplers may be added to a developing bath containing a fair amount of a sulflte.

Another advantage of this invention is that the newcolor couplers are generally soluble in weak bases, such as carbonates, so that they can be added to the developing baths without the Usually the developing baths are only slightly coloredf A great advantage offered by the new class I of color 'couplers is that owingto their wide diversity. the most varying tones can be obtained, which is of utmost importance for the mutual adaptation of the different dyes formed-by color development in a material with two or more layers. 1

Still another advantage of the new color cou plers is that they can quite easily be rendered free from diffusion from one layer into another, which is very important when they are to be incorporated in the emulsion directly. To this purpose condensation with hydrazides contain-. ing a sumcient amount of carbon atoms sufllces.

Our new color couplers can moreover be kept a long time, which is not always possible with the known hydrazones derived from acetoacetic Thus, the invention comprises the color couplers defined above as well as the improved process oi producing color photographic images by means or these color couplers. Furthermore the invention comprises the improved processfof i'orming color. photographic images by the'incorporation inthe photographic emulsion, before or after coating, of a color coupler as defined above and development of such an emulsion after, exposure. The invention also comprises a pho-z 75 Water v tographic emulsion, which contains a color coupier-as defined above and preferably such a color coupler which is-derived from a hydrazide containing' a sufllcient number of carbon atoms to substantially prevent diffusion, as well as a photographic material comprising one or seyeral layers formed of such an emulsion. The invention further includes the process of developing a latent photographic image by means of a color developer comprising in addition to an aromatic amino developing agent a color coupler as above defined, and it includes also a color developer containing these substances. The invention also includes a process or method of .color developlment which comprises developing a latent photographic image by means of an aromatic amino developer in the presence of color couplers as above defined, and eliminating the silver image which is formed during development so that a pounds.

clear and transparent color image remains.

Our invention further includes photographic elements having at least one layer containing a clear and transparent image composed essentially of the product resulting from the coupling "in situ during development of color couplers as above defined, with the oxidation product 0 an aromatic amino developing agent.

The aromatic compounds which may be as developing agents in the present invention-M include the mono-, diand tri-amino-aryl comagents may be mentioned amino-phenols and amino-cresols and their halogen derivatives and amino-naphthols.

The developing agents preferably used and Eiv-v ing the best results in connection with the present invention are the aromatic orthoand'paradiamines, such as orthoand para-phenylenediaminesl These developing agents may be substituted in oneamino group or in the ring or- I in one amino group and in the ring, forming different compounds such as:

Diethyl-para-phenylenediamine,

, Monoethyl-para phenylenediamine,

Dimethyl-para-phenylenediamine, and 3-amino-6-dimethylamino toluene.

' These compounds are usually kept in the salt form, such as hydrochloride or sulfate.

By color development we not only mean the formation of a colored image by the interaction, during the photographic developing process, of a developer and a color coupler but also the formation of a colored image by the action of an insoluble oxidising agent, such as for instance silverferri-cy'anide, present in a photographic layer, or a developing bath which contains. be-

sides the reducing and the other usual constituents, a color coupler as' descrlbed above. This color coupler according to our invention may also be present in the emulsion.

The following developer solutions may for instance-be used to give a com...

Among the mono-amino developing color image according to H2 .'.El'&l1lS. 2.

with Formula 1 gives a magentacolor; the absorption maximum 01' this color is in the correct theoretical position, viz. at 5,500 A and the color has a good transparency for the blue part 01 the spectrum.

Organic solvents, for instance acetone, alcohols or the like, may be used-to dissolve the color can be added to the developing bath without the intervention of organic solvents.

The invention is in no way limited to the use of the color couplers in the developing solution itself. Thus, as above stated, one of the essential products, viz. the color coupler, which during the development form the dye, can also be added to the photographic emulsion, before or after coating, for instance by adsorption upon the silver salts. The other ingredients of the color forming baths, containing chiefly the aromatic ammodeveloper, may be applied later, during the developing process, as a bath.

The present invention maybe utilized in the formation of colored photographic images on plates or papers as well as on film, employing gelatine or other carriers for the silver halide.

The developing process may be used for the developing of photographic material provided with one or several sensitive layers, which are applied on one side or onboth sides of the support.

The silver image formed during developmentcan easily be eliminated. For this purpose a bath. of course, must be used which has no harmful cfiect upon the dye. Thus, a bath consisting of a solution in water of potassium ferricyanide and sodium thiosulfate easily eliminates the silver without destroying the dye. V

Various changes may be'made in the details described in the above specification without descope of the invention.

methylene groups connected by an aliphatic chain containing the hydrazine radical =N--NH-- 2. A photographic'developer for the produc-' tion or colored images, said developer containing a primary aromatic amino developing agent and cyanoacetylhydrazone having, at least two reac- Formosa 2 Diethyl para phenylenediamine hydrochloride gramsi 4 sodium sulfite cryst do 5 Sodium carbonate cryst do 20 Sodium hydroidde do 1 Water ccm 1000 8 C=NNHC o-cmoN ca, "grams" 2v 4 Acetone l Wm 50 Foruse B is added to A.

Forum 3 A 3 amino 6 dimethylaminotoluene hydrochloride grams 4 Sodium sulfite crystdo 5 Potassium carbonate do....; 30 Sodium hydr do 015 Water Mm 1000.

( oNiI-N=o -c'{,-c0c.m (111 (3H3 I "ITEMS" 2 onii-N=u-cm-co-ciiir I Acetone I mm For use B is added to A.

couplers, but as already stated the color couplers tive-methylene groups connected by an aliphati chain containing the hydrazine radical NNH- PIERRE BRUYLANTS.

PHILIBERT LEOP'OLD JOZEF RAYMOND MERcKx. 

